Lock

ABSTRACT

A lock is disclosed comprising an upper locking unit and a lower locking unit, said upper locking unit comprising an opening, a plunger disposed within said opening, said opening being so dimensioned as to permit said plunger to be slidably displaced within said opening, said plunger being of such a material that said plunger is caused to be slidably displaced within said opening by a magnetic force being placed in close proximity thereto, said lower locking unit comprising an opening so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in said upper locking unit when the lower portion of said plunger is disposed in said opening of said lower locking unit whereby said upper locking unit is locked to said lower locking unit when said plunger is disposed within said openings in said upper and lower locking units and whereby said upper locking unit is unlocked from said lower locking unit when a magnetic force is brought into close proximity with said plunger causing said lower portion of said plunger to be removed from within said opening in said lower locking unit.

United States Patent [191 Pratt 1 1 June 5, 1973 [54] LOCK Primary Examiner-Albert G. Craig, Jr. [76] Inventor: Eugene L. Pratt, 717 A Wolcott Atwmey shaffert & Mlner Drive, Philadelphia, Pa. 191 18 [57] ABSTRACT [22] Filed: Apr. 26, 1971 l A lock is disclosed comprising an upper locking unlt PP 137,176 and a lower locking unit, said upper locking unit comprising an opening, a plunger disposed within said 52 US. Cl. ..70/276, 292/184, 292 340, Opening, Said Opening being so dimensioned as to p 292 5 mit said plunger to be slidably displaced within said [51] Int. Cl. ..E05b 47/00 Opening, Said Plunger being of such a material that [58] Field of Search ..70/7, 9, 11, 91, Said p g is caused to be Slidably displaced within 70/95, 97, 101, I29, 276; 292/144, 148, 183, said opening by a magnetic force being placed in close 184, 300, 302, 327 DIG, 32, DIG, 65; proximity thereto, said lower locking unit comprising 16/147, 176 an opening so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in [56] References Cited said upper locking unit when the lower portion of said plunger is disposed in said opening of said lower UNITED STATES PATENTS locking unit whereby said upper locking unit is locked 3,584,485 6/1971 Peterson 70/276 to said lower locking unit when Said Plunger is 3,161,324 12/1964 ONeill ..292/144 X disposed within said openings in said upper and lower 3,626,961 12/1971 Quinones ..292/144 X locking units and whereby said upper locking unit is ganAuker-n unlocked from said lower locking unit when a magewman 2,458,046 1 1949 Audet ..70 91x net: force brought close proxlmlty with Sam plunger causing said lower portion of said plunger to be removed from within said opening in said lower locking unit.

11 Claims, 10 Drawing Figures PATENTEUJUH 51975 SHEET 1 OF 2 3,736,779

mn E/vra', EUGENE 1. Pa?

LOCK

The present invention relates to a lock. More particularly, the present invention relates to a lock that may be applied to cabinet doors to prevent unauthorized entry, especially, unauthorized entry by small children who may be damaged by the contents within the cabinet.

The kitchen, the laundry room, the bathroom and other areas of the home contain cabinets having household items stored therein such as detergents, pesticides, drugs, etc. Many of these items are highly toxic, especially to small children. Since small children are so curious and inquisitive, it is not uncommon for children to obtain entry into these cabinets and to be harmed by the contents therein.

This is not a small problem. For example, in the state of Illinois in 1969, there were over 12,000 cases involving the accidental poisoning of children. In fact, the Executive Director of the Illinois Association for the Mentally Retarded has stated that poisoning is one of the major causes of brain damage among children under the age of 12.

To further illustrate, reports from the Philadelphia Department of Public Health indicate that 5,000 children per year between the crawling age and the age of 6 are hospitalized due to accidental poisoning. The reports from the Philadelphia Department of Public Health also indicate that the number of cases of accidental poisoning is increasing.

Accordingly, it is the object of the present invention to provide a lock to prohibit unauthorized entry into cabinets.

It is a further object of the present invention to provide a lock which may be readily unlocked quickly and conveniently by authorized personnel.

It is still another object of the present invention to provide a lock whose external appearance gives no indication as to how the lock may be opened.

It is yet a further object of the present invention to provide a lock that may be internally mounted within a cabinet so that the external appearance of the cabinet does not indicate that the cabinet is locked, how it is locked, or how it may be opened.

It is another object of the present invention to provide a lock with a self-locking feature so that the cabinet door or doors to be locked may be locked by merely closing them.

Other objects will appear hereinafter.

In accordance with a first embodiment of the present invention, upper and lower locking units are so disposed as to mate and lock with each other. A slidable plunger is disposed within the upper locking unit, and is completely hidden from view. Under the force of gravity, the slidable plunger is displaced to enter an opening in the lower locking unit thereby placing the locking units in their locked position. The locking units may be unlocked by the placement of a magnet in proximity with the plunger whichis magnetically attracted thereto causing the upward displacement of the plunger thereby causing the lower portion of the plunger to be lifted from within the opening in the lower locking unit.

In accordance with another embodiment of the present invention, upper and lower locking units are mounted within a cabinet so that the external appearance of the cabinet in its locked position offers no indication as to whether it is locked, how it was locked, or how it may be opened.

For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown,

FIG. 1a illustrates the positional relationship between the upper and lower locking units ofa first embodiment of the present invention.

FIG. lb illustrates in greater detail the positional relationship of FIG. 1a between the plunger of the upper locking unit and the opening of the lower locking unit.

FIG. 2 is an exploded view of the upper and lower locking units of a first embodiment of the present invention.

FIG. 3 illustrates how the locking units of FIG. 2 may be utilized to lock a specific form of cabinet.

FIG. 4 illustrates how the locking units of FIG. 2 may be utilized to lock another form of cabinet.

FIG. 5 illustrates a second embodiment of the present invention in use with yet another form of cabinet.

FIG. 6 is a cross sectional view ofa third embodiment of the present invention as applied to still another form of cabinet.

FIG. 7 illustrates the third embodiment of the present invention as applied to a further form of cabinet.

FIG. 8 is a cross sectional view taken along lines 8-8 of FIG. 7.

FIG. 9 illustrates a keeper in accordance with the present invention for securing from children the magnet used for opening the cabinet.

Referring to the drawings in particular, FIG. 1a illustrates the disposition of upper locking unit 12 and lower lower locking unit 14 in their locked position. Lower locking unit 14 contains screws 16 and 18 which extend therethrough and allow lower locking unit 14 to be attached to a movable cabinet door or the like. Similarly, upper locking unit 12 contains screws 20 and 22 which permit upper locking unit 12 to be rigidly mounted to a movable cabinet door or the like. Al-

though screws have been disclosed as a means for attachment, it is well within the realm of the present invention to utilize other attachment means such as nails, adhesives, etc.

The topmost portion of upper locking unit 12 is covered by plate 36. Plate 36 may be any material that will readily permit magnetic lines of force to pass therethrough. Immediately below plate 36 in the left hand sector of upper locking unit 12 is a relatively large diameter passage or opening 32 which, as shown in the drawing, becomes a relatively smaller diameter passage or opening 34 in the lower left sector of upper locking unit 12. Disposed within openings 32 and 34 is a plunger 26 which is comprised of a head 30 and a shaft 28. Head 30 is constructed of a material that is attracted by a magnet. Therefore, as shown in FIG. 1b, the placing ofa magnet over the top left sector of upper locking unit 12 causes head 30 and shaft 28 to be upwardly displaced in opening 32. This also causes the upward displacement of shaft 28 within opening 34.

Lower locking unit 14 is so disposed with respect to upper locking unit 12 that passage or opening 24 is disposed immediately below opening 34. Therefore, it is clear that the downward displacement of plunger 26 causes the entrance of shaft 28 into opening 24 of lower locking unit 14. When plunger 26 is downwardly displaced by the force of gravity, shaft 28 enters opening 24 thereby locking upper locking unit 12 with respect to lower locking unit 14. The upward displacement of plunger 26 by the placement ofa magnet thereabove causes shaft 28 to be removed from within opening 24 thereby unlocking lower locking unit 14 from upper locking unit 12.

It should be noted that the appearance of upper locking unit 12 and lower locking unit 14 in their locked position does not indicate how or in what manner the unlocking may be accomplished. Since upper locking unit 12 and lower locking unit 14 are preferably of opaque material and since plate 36 which covers head 30 is also preferably of opaque material, the external appearance of the locked units does not indicate if they are locked, how they were locked, or how they might be unlocked.

FIG. 1b illustrates in greater detail the disposition of shaft 28 within opening 24. As shown in FIG. lb, opening 32 is of such a height that the upward displacement of head 38 and shaft 28 through the action of magnet 44 causes shaft 28 to be entirely withdrawn from opening 24. It is also noted that opening 32 is of a depth to permit the entrance of shaft 28 into opening 24 when magnet 44 is removed permitting head 30 and shaft 28 to be downwardly displaced by the force of gravity.

FIG. 2 illustrates upper locking unit 12 and lower locking unit 14 in exploded view. FIG. 2 shows quite clearly how plate 36 covers upper locking unit 12 and conceals from view head 30. Plate 36 may be affixed to upper locking unit 12 by means of adhesive 42 as shown in FIG. 2. However, it is well within the realm of the present invention to utilize other attachment means such as nails, screws, etc.

As shown in FIG. 2, lower locking unit 14 has contoured edges 38, 40 and 41. Contoured edge 41 (designated in the drawing but not visible due to the angle of the illustration) is similar in shape to contoured edge 40 and is disposed directly opposite thereto. The purpose of these contoured surfaces is to permit lower locking unit 14 to be locked to upper locking unit 12 without the use of a magnet by merely closing the cabinet doors to which locking units 12 and 14 are affixed. When upper locking unit 12 is separated from lower locking unit 14, and head 30 is not upwardly displaced under the force ofa magnet, shaft 28 protrudes beyond the lower surface of upper locking unit 12. However, by sliding upper locking unit 12 over either contoured surface 38, 40 or 41, shaft 28 is forced to ride up onto the top surface of lower locking unit 14 and into open ing 24. Whether or not contoured surface, 38, 40 or 41 is utilized depends upon the manner in which the cabinet doors to which the locking units are attached are hinged. However, it should be noted that there is no necessity that lower locking unit 14 contain contoured surfaces 38, 40 and 41 as it is possible to lock the units by merely using a magnet to cause the upward displacement of head 30 until shaft 28 is disposed on the top surface oflower locking unit 14 at which time the magnet may be removed. This may be desirable if there is a requirement that the units not be locked unless there is some assurance that the magnet is readily locatable to unlock the units. Alternatively, it is possible to use ones finger to raise shaft 28 until it is disposed on the top surface of lower locking unit 14.

FIG. 3 illustrates a cabinet 46 that has affixed thereto the locking units shown in FIG. 2. Access to the interior of cabinet 46 is provided by doors 48 and 50 which are separated by center post 49 of cabinet 46. Door 48 opens by pivoting about hinges 52 and 54. In similar fashion, door 50 opens by pivoting about hinges 56 and 58. When upper locking unit 12 and lower locking unit 14 are in their locked position, it is clear that neither door 48 nor door 50 is permitted to open. After doors 48 and 50 have been opened, they may be returned to their locked position by merely closing doors 48 and 50. This causes shaft 28 of plunger 26 to ride up on either contoured surface 40 or 41 (depending upon which door is closed first) with the result that shaft 28 drops into opening 24 causing the locking of doors 48 and 50.

FIG. 4 shows the locking units of FIG. 2 utilized to lock cabinet doors 62 and 64 of cabinet 60. Cabinet door 62 is opened by movement to the right as shown by the arrow. Cabinet door 64 is opened by movement to the left as shown by the other arrow. As shown in FIG. 4, it is clear that the downward displacement of shaft 28 within opening 24 prohibits the opening of either cabinet door 62 or cabinet door 64. Once opened, cabinet doors 62 and 64 may be locked by merely sliding cabinet doors 62 and 64 to their closed position. This causes shaft 28 to ride up on contoured surface 38 (FIG. 2) causing shaft 28 to drop into opening 24 of lower locking unit 14.

FIG. 5 illustrates a second embodiment of the present invention. Cabinet 66 having frame 88 includes door 68 which is slidable therein in the direction shown by the arrow. Lower locking unit 72 is attached to frame by screws 86 and 88. In a similar manner, upper locking unit 70 is rigidly secured to door 68 by screws 82 and 84. Plate 74 covers the upper portion of upper locking unit 70 and is similar to plate 36 of the first embodiment. Upper locking unit 70 is similar to upper locking unit 12 and includes plunger 76 which is similar to plunger 26 of the first embodiment. Similarly, lower locking unit 72 is similar to lower locking unit 14 with the exception that opening 78 is positioned to permit vertical mounting of lower locking unit 72 to frame 88. Although screws are shown as the means of attachment, other conventional means such as nails, adhesives, etc., may also be utilized. As is evident from FIG. 5, the downward displacement of plunger 76 into opening 78 prohibits the opening of door 68. The upper sur face of lower locking unit 72 may be contoured if the self-locking feature shown in the first embodiment is desired. Alternatively, the self-locking feature may be omitted by eliminating the contoured surface.

FIG. 6 illustrates a third embodiment of the present invention. As shown in FIG. 6, cabinet includes door 92 which is hinged to frame 94 at hinge 108. The top portion of cabinet 90 is covered by plate 96 which is similar in function to plate 36 of the first embodiment. Lower locking unit 98 is rigidly secured to door 92 as shown in the figure. Lower locking unit 98 includes an opening 100 and a contoured end portion 106. Slidably disposed within frame 94 is plunger 102 containing shaft 104. Plunger 102 is so positioned as to cause shaft 104 to enter and pass through opening in lower locking unit 98 upon the downward displacement of plunger 102 within the relatively large diameter opening in frame 94. As shown in FIG. 6, plunger 102, plate 96 and frame 94 perform the function of upper locking unit 12 in the first embodiment. Similarly, lower locking unit 98 performs the function of lower locking unit 14 in the first embodiment. Contoured end portion 186 provides the self-locking feature explained with respect to the first embodiment. Thus, door 92 may be closed and locked by merely closing it within frame 94 thereby causing plunger 102 to ride up onto end portion 106 resulting in the entrance of shaft 104 through opening 100. Door 92 includes knob 110 which may be utilized to open the door after it has been unlocked. A significant feature of the locking unit of the present invention utilized with cabinet 90 is that the external appearance of cabinet 90 when closed does not give any indication that the cabinet is locked or if it is locked or how it is locked. Further, there is no indication as to how cabinet 90 may be opened. I

FIG. 7 shows the third embodiment of the present invention as utilized in a cabinet 1 12 having a frame 114, a door 116, and a covering plate 122. Door 116 is opened by pulling knob 124 thereby causing door 116 to pivot about hinges 118 and 120. As was also explained with respect to FIG. 6, it is clear from FIG. 7 that the external appearance of cabinet 112 gives no indication if it is locked, how it is locked, or how it may be opened. I

FIG. 8 illustrates a cross sectional view taken along lines 8-8 of FIG. 7. As shown in FIG. 8, the locking of door 116 is accomplished by the gravity caused downward displacement of plunger 102 and shaft 104 through opening 100 in lower locking unit 98. To unlock cabinet 112, it is only necessary to place a magnet above plunger 102 to cause the upward displacement of shaft 104 thereby permitting a pulling upon knob 124 to cause door 116 to pivot about hinges 118 and 120. As explained with reference to FIG. 6, contoured portion 106 provides a self-locking feature for plunger 102. If this self-locking feature is to be omitted, contoured portion 106 may be simply straightened so as to project perpendicularly from the plane of door 116.

In order to prevent unauthorized openings of locked cabinets by children, it is important that the magnet used to unlock the cabinet be kept hidden or in a place where children will not be able to remove it therefrom. In accordance with this requirement, there is provided in accordance with the present invention a keeper for securing the magnet. The keeper is horizontally mounted and is comprised of a base 128 which is comprised of such a material so as to attract magnet 44 thereto. Disposed adjacent to base 128 is wall 126 which has an inner periphery which is slightly larger than the outer periphery of magnet 44. Wall 126 is of sufficient height so that the only way magnet 44 can be withdrawn from plate 128 is by removing magnet 44 in a direction almost perpendicular to the plane of base 128. Therefore, if base 28 is horizontally mounted,

. magnet 44 may only be removed from its keeper by lifting it in a substantially upward direction, which is difficult for children to do since the substantial forces of magnetic attraction must be overcome. Thus, as shown in FIG. 9, the magnet is boxed-in to prevent unauthorized removal by children by twisting, sliding or tilting of the magnet which is relatively easy for children to do.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. For example, by way of illustration and not by way of limitation, it is feasible to utilize two parallelly disposed plungers in the upper locking unit and two openings in the lower locking unit and have one magnet effect the simultaneous upward displacement of both plungers. Accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

I claim:

1. A lock comprising an upper locking unit and a lower locking unit, said upper locking unit having a passage, a plunger disposed within said passage, said passage being so dimensioned as to permit said plunger to be slidably displaced within said passage, said plunger being of such a material that said plunger is caused to be slidably displaced within said passage by a magnetic force being placed in close proximity thereto, said lower locking unit having a passage so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in said upper locking unit when the lower portion of said plunger is disposed in said passage of said lower locking unit, an opaque plate which permits magnetic lines of force to be transmitted therethrough covering said passage of said upper locking unit having at least two perpendicularly disposed contoured surfaces to permit said plunger to ride up onto the upper surface of said lower locking unit so that said plunger may be aligned with and drop to 2 position partially within said passage in said lower locking unit, whereby said upper locking unit is locked to said lower locking unit when said plunger is disposed within said passages in said upper and lower locking units and whereby said upper locking unit is unlocked from said lower locking unit when a magnetic force is brought into close proximity with said plunger causing said lower portion of said plunger to be removed from within said passage in said lower locking unit.

2. A lock is accordance with claim 1 wherein said upper locking unit includes means to attach said upper locking unit to a cabinet door and wherein said lower locking unit includes means to attach said lower locking unit to a cabinet door.

3. A lock in accordance with claim 2 wherein said plunger is comprised of a head of a first diameter and a shaft ofa second diameter, said passage of said upper locking unit comprising a first opening having a diameter slightly greater than said first diameter, and a second opening having a diameter slightly greater than said second diameter, said first opening leading into said second opening, said head of said plunger being slidably disposed within said first opening and said shaft of said plunger being slidably disposed within said first and said second openings and within said passage of said lower locking unit.

4. A lock in accordance with claim 1 wherein said upper locking unit is attached to a first cabinet door, said lower locking unit is attached to a second cabinet door, and said first and said second cabinet doors open by pivoting about parallelly disposed axes.

5. A lock in accordance with claim 1 wherein said upper locking unit is attached to a first cabinet door, said lower locking unit is attached to a second cabinet door, and said first and said second cabinet doors open by sliding in parallelly disposed paths.

6. A lock in accordance with claim 1 wherein said upper locking unit is attached to a first cabinet door and said lower locking unit is attached to the frame of the cabinet.

7. A lock in accordance with claim 1 further including a magnet which when brought into close proximity with said plunger attracts said plunder causing said plunger to be removed from within said passage in said lower locking unit.

3. A locking in accordance with claim 7 further including a keeper for said magnet, said keeper comprising a base to which said magnet is attracted, a wall surrounding said base having a height less than the height of said magnet, the inner periphery of said wall having a length slightly greater than the outer periphery of said magnet when disposed within said wall, the height and inner periphery of said wall and the magnetic attraction between said base and said magnet being such that the magnet may not be removed from its keeper by twisting, sliding, or tilting of the magnet but can only be removed by lifting said magnet in a direction substantially perpendicular to said base.

9. A lock comprising an upper locking unit and a lower locking unit, said upper locking unit having a passage, a plunger disposed within said passage, said passage being so dimensioned as to permit said plunger to be slidably displaced within said passage, said plunger being of such a material that said plunger is caused to be slidably displaced within said passage by a magnetic force being placed in close proximity thereto, said lower locking unit having a passage so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in said upper locking unit when the lower portion of said plunger is disposed in said passage of said lower locking unit, an opaque plate which permits magnetic lines of force to .be transmitted therethrough covering said passage of said upper locking unit at the upper surface of said upper locking unit, said lower locking unit having two oppositely disposed contoured surfaces to permit said plunger to ride up onto the upper surface of said lower locking unit during relative motion between said upper and lower locking units so that said plunger may be aligned with and drop to a position partially within said passage in said lower locking unit, whereby said upper locking unit is locked to said lower locking unit when said plunger is disposed within said passages in said upper and lower locking units and whereby said upper locking unit is unlocked from said lower locking unit when a magnetic force is brought into close proximity with said plunger causing said lower portion of said plunger to be removed from within said passage in said lower locking unit.

10. A lock comprising an upper locking unit and a lower locking unit, said upper locking unit having a passage, a plunger disposed within said passage, said passage being so dimensioned as to permit said plunger to be slidably displaced within said passage, said plunger being of such a material that said plunger is caused to be slidably displaced within said passage by a magnetic force being placed in close proximity thereto, said lower locking unit having a passage so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in said upper locking unit when the lower portion of said plunger is disposed in said passage of said lower locking unit, an opaque plate which permits magnetic lines of force to be transmitted therethrough covering said passage of said upper locking unit at the upper surface of said upper locking unit, said lower locking unit having at least two contoured surfaces disposed so as to permit said plunger to ride up onto the upper surface of said lower locking unit irrespective of the direction in which said upper locking unit is moved relative to said lower locking unit so that said plunger may be aligned with and drop to a position partially within said passage in said lower locking unit, whereby said upper locking unit is locked to said lower locking unit when said plunger is disposed within said passages in said upper and lower locking units and whereby said upper locking unit is unlocked from said lower locking unit when a magnetic force is brought into close proximity with said plunger causing said lower portion of said plunger to be removed from within said passage in said lower locking unit.

11. A lock in accordance with claim 10, wherein said at least two contoured surfaces includes a third contoured surface which permits either of said upper and lower locking units to be moved to a locking position followed by the other of said locking units into said locking position without interference by the plunger. 

1. A lock comprising an upper locking unit and a lower locking unit, said upper locking unit having a passage, a plunger disposed within said passage, said passage being so dimensioned as to permit said plunger to be slidably displaced within said passage, said plunger being of such a material that said plunger is caused to be slidably displaced within said passage by a magnetic force being placed in close proximity thereto, said lower locking unit having a passage so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in said upper locking unit when the lower portion of said plunger is disposed in said passage of said lower locking unit, an opaque plate which permits magnEtic lines of force to be transmitted therethrough covering said passage of said upper locking unit having at least two perpendicularly disposed contoured surfaces to permit said plunger to ride up onto the upper surface of said lower locking unit so that said plunger may be aligned with and drop to 2 position partially within said passage in said lower locking unit, whereby said upper locking unit is locked to said lower locking unit when said plunger is disposed within said passages in said upper and lower locking units and whereby said upper locking unit is unlocked from said lower locking unit when a magnetic force is brought into close proximity with said plunger causing said lower portion of said plunger to be removed from within said passage in said lower locking unit.
 2. A lock is accordance with claim 1 wherein said upper locking unit includes means to attach said upper locking unit to a cabinet door and wherein said lower locking unit includes means to attach said lower locking unit to a cabinet door.
 3. A lock in accordance with claim 2 wherein said plunger is comprised of a head of a first diameter and a shaft of a second diameter, said passage of said upper locking unit comprising a first opening having a diameter slightly greater than said first diameter, and a second opening having a diameter slightly greater than said second diameter, said first opening leading into said second opening, said head of said plunger being slidably disposed within said first opening and said shaft of said plunger being slidably disposed within said first and said second openings and within said passage of said lower locking unit.
 4. A lock in accordance with claim 1 wherein said upper locking unit is attached to a first cabinet door, said lower locking unit is attached to a second cabinet door, and said first and said second cabinet doors open by pivoting about parallelly disposed axes.
 5. A lock in accordance with claim 1 wherein said upper locking unit is attached to a first cabinet door, said lower locking unit is attached to a second cabinet door, and said first and said second cabinet doors open by sliding in parallelly disposed paths.
 6. A lock in accordance with claim 1 wherein said upper locking unit is attached to a first cabinet door and said lower locking unit is attached to the frame of the cabinet.
 7. A lock in accordance with claim 1 further including a magnet which when brought into close proximity with said plunger attracts said plunder causing said plunger to be removed from within said passage in said lower locking unit.
 8. A locking in accordance with claim 7 further including a keeper for said magnet, said keeper comprising a base to which said magnet is attracted, a wall surrounding said base having a height less than the height of said magnet, the inner periphery of said wall having a length slightly greater than the outer periphery of said magnet when disposed within said wall, the height and inner periphery of said wall and the magnetic attraction between said base and said magnet being such that the magnet may not be removed from its keeper by twisting, sliding, or tilting of the magnet but can only be removed by lifting said magnet in a direction substantially perpendicular to said base.
 9. A lock comprising an upper locking unit and a lower locking unit, said upper locking unit having a passage, a plunger disposed within said passage, said passage being so dimensioned as to permit said plunger to be slidably displaced within said passage, said plunger being of such a material that said plunger is caused to be slidably displaced within said passage by a magnetic force being placed in close proximity thereto, said lower locking unit having a passage so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in said upper locking unit when the lower portion of said plunger is disposed in said passage of said lower locking unit, an opaque plate which permits magnetic lines of forcE to be transmitted therethrough covering said passage of said upper locking unit at the upper surface of said upper locking unit, said lower locking unit having two oppositely disposed contoured surfaces to permit said plunger to ride up onto the upper surface of said lower locking unit during relative motion between said upper and lower locking units so that said plunger may be aligned with and drop to a position partially within said passage in said lower locking unit, whereby said upper locking unit is locked to said lower locking unit when said plunger is disposed within said passages in said upper and lower locking units and whereby said upper locking unit is unlocked from said lower locking unit when a magnetic force is brought into close proximity with said plunger causing said lower portion of said plunger to be removed from within said passage in said lower locking unit.
 10. A lock comprising an upper locking unit and a lower locking unit, said upper locking unit having a passage, a plunger disposed within said passage, said passage being so dimensioned as to permit said plunger to be slidably displaced within said passage, said plunger being of such a material that said plunger is caused to be slidably displaced within said passage by a magnetic force being placed in close proximity thereto, said lower locking unit having a passage so dimensioned as to receive said plunger, means retaining the upper portion of said plunger in said upper locking unit when the lower portion of said plunger is disposed in said passage of said lower locking unit, an opaque plate which permits magnetic lines of force to be transmitted therethrough covering said passage of said upper locking unit at the upper surface of said upper locking unit, said lower locking unit having at least two contoured surfaces disposed so as to permit said plunger to ride up onto the upper surface of said lower locking unit irrespective of the direction in which said upper locking unit is moved relative to said lower locking unit so that said plunger may be aligned with and drop to a position partially within said passage in said lower locking unit, whereby said upper locking unit is locked to said lower locking unit when said plunger is disposed within said passages in said upper and lower locking units and whereby said upper locking unit is unlocked from said lower locking unit when a magnetic force is brought into close proximity with said plunger causing said lower portion of said plunger to be removed from within said passage in said lower locking unit.
 11. A lock in accordance with claim 10, wherein said at least two contoured surfaces includes a third contoured surface which permits either of said upper and lower locking units to be moved to a locking position followed by the other of said locking units into said locking position without interference by the plunger. 